Wheeled carriages for supporting a patient in a substantially horizontal position are well known in the art and a representative example of an early version of such a device is illustrated in Dr. Homer H. Stryker's U.S. Pat. No. 3,304,116, reference to which is incorporated herein. Other of such wheeled carriages are disclosed in U.S. Pat. Nos. 6,230,343 and 6,264,006, both of which are presently owned by the Assignee of record for this invention. Reference to these latter two patents is also to be incorporated herein.
During the assembly of wheeled carriages, strict control over tolerances is always a requirement. This is especially true in mechanisms which are to facilitate the simultaneous raising function of both of the hydraulic jacks onboard the wheeled carriage. In order to effect a simultaneous raising of the hydraulic jacks, and thereby the patient supporting surface, it is essential that the stroke applied to the pumps is the same in order to maintain the patient supporting surface level. Accordingly, a structure which will facilitate the simultaneous raising of the hydraulic jacks and assuring that the stroke applied to each of the hydraulic jacks is the same is highly desired.
It is also essential that there be provided a control for facilitating a lowering of the hydraulic jacks independently of one another, as well as simultaneously. U.S. Pat. No. 6,230,343, mentioned above, provides one type of mechanism for facilitating these tasks. However, it is essential that each of the valves on the hydraulic jacks that controls the lowering function be activated to the same extent during a simultaneous lowering in order to maintain the patient supporting surface horizontal. Thus, a control mechanism for facilitating a lowering of the hydraulic jacks, either independently as well as simultaneously, and which facilitates easy adjustment to compensate for variations and tolerance is highly desirable.
It is also essential that the wheeled carriage be provided with a brake mechanism and U.S. Pat. No. 6,264,006, mentioned above, provides one form of braking mechanism. To simplify the construction of the brake mechanism and thereby effect a reduction in manufacturing expense is always a goal of every improvement. The brake mechanism disclosed herein is no exception.